1. Field of the Invention
Aspects of the present invention relate to an image forming apparatus, and more particularly, to an image forming apparatus having an image scanning unit for scanning an image recorded on a document.
2. Description of the Related Art
An image forming apparatus is a device for printing an image on a sheet of paper. However, in recent years, more office applications require the use an image forming apparatus having an image scanning function (referred to as combined scanner/printer). The apparatus having the image scanning function (for example, a facsimile or scanner function) captures an image recorded on a document using an image sensor, and converts the image into digital image information to reproduce it on a piece of paper or a display unit.
To perform the scanning function, the image forming apparatus is provided with an image scanning unit. FIG. 1 shows one example of a conventional image scanning unit 10. Referring to FIG. 1, the image scanning unit 10 includes a flat transparent window 11 on which a document (not shown) that is to be scanned is laid, and an image sensor 15 running linearly under the transparent window 11 for capturing an image recorded on the document through a scanning process. A guide shaft 30 is disposed below the image sensor 15 to guide the linear movement of the image sensor 15 as indicated by the arrow.
The image sensor 15 is mounted to an image sensor carrier 20 made of metal. The guide shaft 30 is inserted into a guide shaft holder 25 that can reciprocate along the guide shaft 30. The image sensor carrier 20 is connected to the glide shaft holder 25 by a bolt 27. A spring 23 is interposed between the image sensor carrier 20 and the image sensor 15 so that the image sensor 15 is biased against the transparent window 11. The guide shaft holder 25 is connected to a belt (not shown) operated by a motor (not shown) in the same direction as a longitudinal direction of the guide shaft 30.
When an image reading command is input to the image scanning unit 10, the belt is operated by the motor, and thus the guide shaft holder 25 connected to the belt runs along the guide shaft 30. Hence, the image sensor 15 mounted to the image sensor carrier 20 runs linearly to scan the image recorded on the document, while in contact with the transparent window 11.
However, since the image sensor carrier 20 and the guide shaft holder 25 are separately manufactured and assembled, a size, in particular, a height, of the assembly is increased. Therefore, it is difficult to miniaturize the image forming apparatus having the image scanning unit. Also, because of the assembling process of the image scanning unit, the entire assembling time of the image forming apparatus increases, and dimensional tolerances between components accumulate and thereby the accuracy of a completed product is low. In addition, since the image sensor carrier 20 is made of metal, induced static electricity may result in malfunction or damage of the image sensor 15 or motor.